1School of Physics and Opto-electronics Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 2Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology (CICAEET), Nanjing 210044 3State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071
Abstract：Ultrafast dissociation dynamics of chloroiodomethane (CH$_{2}$ICl) in the B band is studied by femtosecond time-resolved time-of-flight (TOF) mass spectrometry. Time-resolved TOF mass signal of parent ion (CH$_{2}$ICl$^{+})$ and main daughter ion (CH$_{2}$Cl$^{+})$ are obtained. The curve for the transient signal of CH$_{2}$ICl$^{+}$ is simple and can be well fitted by an exponential decay convoluted with a Gaussian function. The decay constant determined to be less than 35 fs reflects the lifetime of the B band. Significant substituent effects on photodissociation dynamics of CH$_{2}$ICl compared with CH$_{3}$I are discussed. The dissociation time from the parent ion CH$_{2}$ICl$^{+}$ to the daughter ion CH$_{2}$Cl$^{+}$ is determined in the experiment. The optimized geometry of the ionic state of CH$_{2}$ICl and the ionization energy are calculated for further analysis of the measurements. In addition, compared with the parent ion, a new decay component with time constant of $\sim $596 fs is observed for CH$_{2}$Cl$^{+}$, and reasonable mechanisms are proposed for the explanation.
Frisch M J, Trucks G W, Schlegel H B et al 2009 Gaussian 09, Revision E. 01 (Wallingford: Gaussian Inc.)
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2017, Vol. 34 
